UC-NRLF 
 
 DSS 
 
f 
 
 REESE LIBRARY 
 
 <)! 'I in: 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Accessions No. 
 
 . Class No. 
 
SMOKELESS POWDEK 
 
 AND 
 
 ITS INFLUENCE ON 
 
 GUN CONSTRUCTION. 
 
 BY 
 
 JAMES ATKINSON LONGRIDGE, 
 
 MEM. INST. CIVIL ENG. ; HON. MEM. OF NORTH OF ENGLAND INSTITUTE 
 
 OP MINING AND MECHANICAL ENGINEERS ; 
 
 AUTHOR OF <A TREATISE ON THE APPLICATION OF WIRE TO THE 
 
 CONSTRUCTION OF ORDNANCE*; 'INTERNAL BALLISTICS,' 
 
 ETC., ETC. 
 
 E. & F. N. SPON, 125, STBAND, LONDON. 
 
 NEW YORK: 12, CORTLANDT STREET. 
 
 1890. 
 
 Price 3s. 
 
REESE LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 ^Heceived , i8g . 
 
 | ; 
 
 ^Accessions No..... Class No..... ..... t 
 
SMOKELESS POWDER 
 
 AND 
 
 ITS INFLUENCE ON 
 
 GUN CONSTEUCTION. 
 
 IV BE 
 
SMOKELESS POWDER 
 
 AND 
 
 ITS INFLUENCE ON 
 
 GUN CONSTRUCTION 
 
 BY 
 
 JAMES ATKINSON LONGRIDGE, 
 
 MEM. INST. CIVIL ENG. ; HON. MEM. OF NORTH OF ENGLAND INSTITUTE 
 
 OF MINING AND MECHANICAL ENGINEERS; 
 
 AUTHOR OF 'A TREATISE ON THE APPLICATION OF WIRE TO THE 
 
 CONSTRUCTION OF ORDNANCE'; 'INTERNAL BALLISTICS,' 
 
 ETC., ETC. 
 
 E. & F. N. SPON, 125, STRAND, LONDON. 
 
 NEW YORK : 12, CORTLANDT STREET, 
 1890. 
 
V 
 
IN the last chapter of my recent treatise on * Internal 
 Ballistics' I alluded to the new powders which were then 
 attracting the attention of artillerists. 
 
 Keferring to their probable nature, I observed that the 
 introduction of any ingredients which would either increase 
 the volume of gas or its temperature, or both together, 
 would not only explain the apparently anomalous action of 
 these new powders, but probably result in the discovery of a 
 still more powerful agent. 
 
 Since then this has apparently been accomplished, and the 
 old charcoal powder appears to be doomed to yield to this 
 more powerful rival. 
 
 But the adoption of this rival, whose properties are as yet 
 only imperfectly known, is not to be viewed without anxiety. 
 Can it be used with advantage, and above all with safety, in 
 our new type forged steel guns ? If not, what changes will 
 its use involve in gun construction ? What will be its effect 
 as regards erosion ? How will it be affected by storage and 
 change of climate ? 
 
 These are important questions, to which I do not pretend to 
 give complete answers, but I hope that the following remarks 
 will be of some use in directing attention to the problems 
 upon the solution of which future gun construction and 
 ballistic practice largely depend. 
 
 J. A. LONGKIDGE. 
 
 GEEVE D'AZETTE, JERSEY. 
 August 1890. 
 
CONTENTS 
 
 I. INTRODUCTORY -. . . . . 1 
 
 II. NATURE OF THE POWDER PRODUCTS OF COMBUS- 
 TION POTENTIAL FORCE COMPARISON WITH 
 OLD POWDERS . . . . , 4 
 
 III. BALLISTIC EFFECT OF NEW POWDERS IN FRENCH 
 AND GERMAN GUNS COMPARISON OF B.N. AND 
 NOBEL'S POWDER 9 
 
 IV. PRESSURES IN THE CHASE WITH NEW POWDER 
 COMPARISON WITH PRESSURES FROM PEBBLE 
 POWDER 17 
 
 V. EFFECT OF THE NEW POWDER ON EXISTING GUNS . . 24 
 
 VI. INFLUENCE OF THE NEW POWDER ON THE DESIGN 
 
 OF GUNS 35 
 
 VII. CONCLUSION 39 
 
 APPENDICES 42 
 
 POSTSCRIPT 49 
 
SMOKELESS POWDER. 
 
 INTRODUCTORY. 
 
 1. In few paths of science has the march of progress in 
 the latter part of the nineteenth century been more remark- 
 able than in the development of material for warfare. 
 
 2. Less than half a century ago, the heaviest guns in our 
 service were the old 68-pounders, weighing about five tons, 
 and firing, with a charge of 20 Ibs. of powder, a spherical 
 68 Ib. projectile to which it gave a velocity of about 1500 feet 
 per second a ballistic effect equal to an energy of 1060 foot- 
 tons. 
 
 3. The heaviest service gun of the present day is the 
 110-ton gun, firing a projectile of 1800 Ibs., with a charge of 
 850 Ibs. of powder, and a velocity of 2100 feet per second, 
 equivalent to an energy of 55,000 foot-tons. 
 
 4. In the absence, in this country, of the definite know- 
 ledge of the action and properties of powder (acquired through 
 the researches of M. Sarrau. in France), the adaptation of 
 the powder to the gun, and, vice versa, of the gun to the 
 powder, has been a problem, the solution of which, so far 
 as it has been solved, is of an empirical nature, so that the 
 progress made in gun construction and powder manufacture 
 has been of a somewhat erratic description. 
 
 5. After the day of pebble powder came that of P 2 or 
 C and C 2 , then that of prismatic, succeeded by that of 
 brown cocoa, and finally that of the so-called E.X.E., which 
 
 B 
 
2 SMOKELESS POWDER. 
 
 a few months ago was looked upon as the ne plus ultra of 
 gunpowder for heavy guns. 
 
 6. The line taken by gunmakers has been tolerably con- 
 sistent throughout. They have aimed at reducing the strength 
 of the powder, keeping down the pressure, and making up for 
 this by increased charges, enlarged powder chambers, and 
 increased length of gun. 
 
 Following out this line they have arrived at charges of 
 one-half, or more, of the weight of the projectile, and at guns 
 of 30 to 40 calibres in length, but with a maximum pressure 
 limited to about 17 tons per square inch. 
 
 7. In vain the argument has been urged that, by strengthen- 
 ing the guns instead of weakening the powder, the same 
 ballistic results could be obtained with greater convenience 
 and less expense. It has been shown, both theoretically and 
 practically, that wire guns can be made as safe under a 
 pressure of 30 tons as forged steel guns under a pressure of 
 17 tons ; but though a few experiments in this direction have 
 been made at Woolwich, they have been made in a half- 
 hearted way, extending over long intervals of time, daring 
 which the construction of the type of* forged steel gun has 
 been rapidly proceeded with, and may be said practically to 
 include the whole of our new armament. 
 
 8. These latter guns are designed specially for the use of 
 such powders as the brown cocoa and E.X.E., that is to 
 say, powder of which a very large charge is required. 
 
 9. Until quite recently our artillerists have been in a 
 happy frame of mind. They had got, or were very rapidly 
 getting a sufficient supply of large guns of what they thought 
 to be the best possible type, and they had the new E.X.E. 
 powder, the best powder in the world. They had but to rest 
 and be thankful. 
 
 10. That rest has been of short duration. From Germany 
 and France came rumours of a new powder giving wonder- 
 ful ballistic results, and at the same time smokeless, or 
 nearly so. 
 
 11. Although much secrecy has been maintained with 
 
SMOKELESS POWDER. 3 
 
 respect to the nature of the new powders, yet the results have 
 been so far made public, that it is no longer doubtful that 
 they will give ballistic results largely exceeding those obtained 
 from cocoa and E.X.E., with considerably reduced charges 
 and no excessive maximum pressure. 
 
 12. This being so, the question arises, how far are our 
 new type guns suited to the new powder, and to what extent 
 shall we require a new armament, in order to reap the full 
 advantage of the new powder ? It is proposed to discuss 
 these questions by the light of such knowledge as the author 
 can bring to bear upon the subject. 
 
 13. This knowledge is too limited to enable him to produce 
 a "treatise on the use of smokeless powder," but it may 
 perhaps be useful in explaining in some degree the difference 
 of action between the old and new powders, and the approxi- 
 mate results obtained by the use of the latter, both as 
 regards ballistic effect and the development of construction 
 of guns suitable to its use. 
 
 14. The subject is divided into the following parts : 
 The nature of the new powder and the results of its de- 
 composition as regards the volume of gas produced per unit 
 of weight, the heat evolved, the temperature of combustion 
 and a comparison with pebble powder, as a type of the old 
 powders, the " Potential " and " Force " of the powder. 
 
 An examination of the ballistic effects of the new powder 
 in French and German guns. 
 
 An inquiry into the pressures in the chase of Canet's 
 15 cm. Q.F. gun, with B.N. powder, and a comparison with a 
 full charge of pebble powder in the same gun. 
 
 An examination into the effect of using the new ^powder 
 in the existing new type forged steel gun. 
 
 A few remarks on the influence of the new powder on the 
 design of guns, and finally some general conclusions. 
 
 B 2 
 
SMOKELESS POWDER. 
 
 II. 
 
 NATURE OF THE POWDER PRODUCTS OF COMBUSTION 
 POTENTIAL FORCE COMPARISON WITH OLD POWDERS. 
 
 15. The very remarkable results which have been recently 
 obtained from smokeless powder in France and Germany, 
 point to an entire revolution in artillery practice, as well as 
 to a complete revision of the system of gun construction and 
 the formulae of internal ballistics. 
 
 16. M. Sarrau's formulae of velocity and pressure, which 
 are very approximately correct for charcoal powders, such as 
 the ordinary black and brown powders, are no longer appli- 
 cable to the case of the new powders which give much higher 
 velocities with smaller charges and reduced pressures. This 
 must consequently lead to modifications in the proportions 
 of guns, if it be admitted that these proportions are de- 
 pendent on the pressures existing in different portions of the 
 gun. 
 
 17. The superior results obtained from the new powders 
 are mainly due to the fact that, with them, nearly the whole 
 of the powder is converted into permanent gases, whereas 
 with the old powders only about 43 per cent, is so converted, 
 the remaining 57 per cent, being inert matter existing in the 
 gun in the form of a very finely diffused liquid, which, when 
 cooled down, solidifies ; and is not only mainly the cause 
 of the smoke, but also in all probability one cause of the 
 excessive erosion. 
 
 18. Although the chemical constitutions of the new 
 powders are kept as secret as possible, they are probably all 
 closely allied to that of Nobel's smokeless powder, that is to 
 say, the main ingredients are nitre-cellulose and nitro- 
 glycerine, to which is added nitrate or perchloride of 
 ammonia and a little camphor. 
 
U IT 171 
 
 'ELESS POWDER. 
 
 SMOK 
 
 19. An analysis of the reactions which take place on the 
 explosion of this mixture is given in the Appendix A, and 
 from this it appears that the whole of the products consist of 
 permanent gases and watery vapour, the volume of which 
 amounts to about 705 cubic centimetres for each gramme of 
 powder. 
 
 20. Further, that the heat evolved, after allowing for the 
 vaporisation of the water, is about 1 7143 French units per 
 gramme of powder. 
 
 21. The mean specific heat of the products is found to be 
 about -1989, and their theoretic temperature about 8673 C. 
 
 22. Appendix B contains a similar examination of the 
 results of combustion of pebble powder, which may be taken 
 as a type of the old powders, from which it appears that the 
 following are the results : 
 
 Volume of gas from 1 gr. of powder .. 286 cm. cube. 
 
 Gramme units of heat 690*2 
 
 Mean specific heat -187 
 
 Theoretic temperature of products .. 4:750 C. 
 
 23. The temperatures above calculated may be called the 
 " Theoretic or Potential Temperature." The actual tempera- 
 tures are probably not more than one-half, owing partly to 
 the cooling effect of the walls, and partly to the increase of 
 the specific heat at the high temperature and pressure exist- 
 ing in a gun ; but they probably represent the relative effect 
 of the two powders as regards the temperature of the pro- 
 ducts of combustion. 
 
 24. The following comparison of the two powders may 
 therefore be made : 
 
 
 Pebble. 
 
 Nobel's. 
 
 Volume of gas at C. and '76 metres from 
 
 TinwrlpT 
 
 1 gramme ofi 
 
 286 
 
 690-2 
 187 
 4750 
 
 705 
 
 1714-8 
 199 
 
 8673C. 
 
 Gramme units of heat evolved from 1 gramme 
 Mean specific heat of products 
 
 Theoretic temperature of products 
 
 
 
6 SMOKELESS POWDER. 
 
 Potential of NobeTs Powder. 
 
 25. By the " Potential " is meant the mechanical equiva- 
 lent of the heat developed by the combustion of unit of 
 weight of the powder, or E Q ; when Q is the quantity of 
 heat evolved, E = 436 in French unities, or 772 in English 
 unities. Now it has been shown that Q = 1*714 units per 
 gramme, or 1714 per kilogramme. 
 
 436 x 1714 
 Therefore, Potential = iQOO = ^^ ' ^ me tre-tons 
 
 per kilogramme, or 1095 foot-tons per Ib. of powder. 
 
 26. In the treatise on ' Internal Ballistics ' * (page 8), 
 there is a table of the " Potentials " of various explosives, 
 and that of pebble powder is given as 460 foot-tons per Ib., 
 or considerably less than the half of that of Nobel's powder ; 
 but, as was there observed, the " Potential " of an explosive 
 must not be confounded with the mechanical effect which 
 may be obtained from it, nor with the pressure developed by 
 its combustion in a closed vessel. 
 
 27. At page 50, ' Internal Ballistics/ the symbol "/" was 
 used to denote what is called by M. Sarrau, the " force " of 
 the powder, and it was defined by the relation 
 
 Po Vp TQ 
 
 7 " 273 ' 
 
 where p Q is the atmospheric pressure = 103 33 kilog. per 
 
 square decimetre ; 
 
 V Q is the volume of gases from unit of weight at tem- 
 perature zero and atmospheric pressure ; 
 T is the absolute temperature of combustion. 
 Taking the kilogramme as unit of weight, the volume of 
 gas is, for Nobel's powder, 705 x 1000 cm. 3 or 705 dm. 3 
 
 If the actual temperature of combustion be taken as 
 one-half of the theoretic value, or 4326 C., the absolute 
 temperature 
 
 = 4326 + 273 = 4599. 
 
 * ' Internal Ballistics,' by J. A. Longridge. Spon, London, 1889. 
 
Therefore / = 
 
 SMOKELESS POWDER. 
 103-33 x 705 x4599 
 
 273 
 
 = 1,227,022 kilogrammes per square decimetre. 
 The value of / for pebble powder is given at page 51, 
 ' Internal Ballistics,' as 263,600, consequently the ratio of/, 
 
 1227022 
 
 as between Nobel's powder and pebble, is = 4 655. 
 
 Zoobuu 
 
 28. The " force," /, as denned by M. Sarrau, is the abso- 
 lute pressure of powder exploded in a close vessel entirely 
 filled ; that is to say of gravimetric density = 1, and with 
 
 ordinary powder p = f - - , where a is the proportion of 
 
 non-gaseous matter, which, with ordinary powders, is about 
 57 of the weight. In Nobel's powder a = 0, consequently 
 p =/A and if A = 1, p =/= 1,227,022 = 122 '7 kilog, per 
 mm. 2 = 78 '52 tons per square inch, which is nearly double 
 that of pebble powder. 
 
 29. It is therefore apparent that the Nobel powder is 
 capable of producing much higher pressure than the pebble, 
 and yet in practice it gives higher velocity with less 
 charges and lower pressures. 
 
 This apparent paradox is easily seen to be due to the 
 absence of inert matter, the whole of the powder being con- 
 verted into gas, instead of only 43 per cent, as in pebble 
 powder, and the total volume of gas being 705 cm. 3 per 
 gramme of powder, against 286 cm. 3 for pebble, whilst at 
 the same time the temperature of combustion is about 
 double. 
 
 30. Actual Pressure in gun. The actual pressures in guns 
 are of course much below the calculated values of p, for two 
 reasons : first, because there is a loss of temperature due to 
 the cooling action of the chamber walls, and secondly, 
 because by the time the whole of the charge is burnt, the 
 projectile has moved a considerable way along the chase 
 and so increased the space to be filled by the evolved 
 
 If, for instance, there be a maximum pressure of 15 tons in 
 
8 SMOKELESS POWDER. 
 
 the gun (assuming for the moment that there is no loss of 
 heat), we have 
 
 and making 
 
 p = 78-52, and p = 15, 
 
 we get 
 
 v = v x 3 506 ; 
 
 so that, if the rate of burning of the powder were suitable, a 
 full charge of gravimetric density = 1 might be fired, and 
 yet the maximum pressure not exceed 15 tons per square 
 inch, which would be attained when the projectile had moved 
 3 ' 506 times the length of the charge along the chase. 
 
 31. Another advantage will probably be the absence of 
 fouling, as the whole of the matter is converted into gases, 
 which leave little or no residuum in the gun. 
 
 32. Erosion. As regards erosion, experience must decide. 
 But it may be said that on the one hand, the products of 
 combustion being entirely gaseous, instead of a mixture of 
 gas and fluids, will probable erode less ; whilst on the other 
 hand that the increased temperature and volume will tend 
 to augment that erosion. 
 
 With the new powder, the temperature no doubt falls 
 more rapidly than with the ordinary powder, because the 
 loss of heat being a function of the difference of temperature 
 between the gases and the gun, is greater with high tempera- 
 tures ; whilst on the other hand, with ordinary powder, it is 
 quite possible that whilst the guns are expanding, heat is 
 communicated to them from the highly heated liquid, arising 
 from the non-gaseous portion of the charge diffused through 
 them. The question of erosion must therefore be determined 
 by experience. So far as our present knowledge goes, the 
 smokeless powder in this respect appears to possess the 
 advantage. 
 
SMOKELESS POWDER. 
 
 III. 
 
 BALLISTIC EFFECT OF NEW POWDERS IN FRENCH AND 
 GERMAN GUNS COMPARISON OF B.N. AND NOBEL*S 
 POWDER. 
 
 33. Formulas for Pressure and Velocity. It is not surprising 
 that the formulae which represent the ballistic action of the 
 old powders are found to be inapplicable to the new powders, 
 and although it is probable that M. Sarrau has already so 
 modified his formula as to make it represent the action of 
 the new powder, it is scarcely likely that the results of his 
 investigations will be made public at present. 
 
 34. Although the experimental data published are very 
 limited, it will not be without interest to examine them care- 
 fully. These data are contained in notices of results of 
 firing, obtained at Essen in July and August 1889, with 
 Nobel's powder fired from four different guns, and of the 
 results obtained from the French B.N. powder fired from 
 10 cm. and 15 cm. guns, or 3*937 and 5*90 inches calibre 
 respectively. 
 
 35. An examination of these results leads to a rather 
 remarkable conclusion, which, however, must be taken with 
 all reserve. 
 
 It is as follows : 
 
 1st. The muzzle velocity of the projectile is proportional to 
 the f th power of the weight of charge. 
 
 2nd. The maximum pressure in the gun is proportional to 
 the square of the weight of the charge. 
 
 (1) 
 P = B w 2 . (2) 
 
 The coefficients A and B are not constants, but are composed 
 
10 SMOKELESS POWDER. 
 
 of various factors, which are functions of the form, dimension, 
 and rate of burning of the grain in fact, what are called by 
 M. Sarrau the " characteristics of the powder of the weight 
 of the projectile, the calibre of the gun, and the length of 
 travel of the projectile. 
 
 In M. Sarrau's formula, he introduces another factor A, 
 the gravimetric density, but this is in itself a function of the 
 weight of charge, and of the calibre of the gun. 
 
 Taking, for instance, M. Sarrau's monomial formula for 
 velocity, as given at page 98, * Internal Ballistics/ 
 
 where H is a factor containing the " force " and " charac- 
 teristics " of the powder ; 
 
 w = weight of charge ; 
 A = gravimetric density ; 
 I = length of travel of projectile ; 
 W = weight of projectile ; 
 c calibre of gun. 
 
 Now, if X = equivalent length of chamber, 
 weight of charge 
 
 capacity of chamber 7854: c 2 A. 
 substituting which in the above we get 
 
 <^ 
 
 
 and it is the part within the bracket that is represented by 
 A in (1). 
 
 In like manner Sarrau's formula for pressure is 
 
 2 Aw'W* 
 = K o" - 2 > 
 
SMOKELESS POWDER. 
 
 11 
 
 by substituting 
 
 7854 
 
 for A becomes 
 
 1-75 
 
 (4) 
 
 and the part within the bracket represents the B in (2). 
 
 36. From this it appears that in passing from the old to 
 the new powders, the index of w is increased from f- to f in 
 the expressions for velocity ; and from 1 75 to 2 in that for 
 pressure, an increase which might be anticipated from the 
 absence of inert matter in the products of combustion of the 
 new powders. 
 
 The coefficients A and B of course are different with dif- 
 ferent guns, and different brands of powder. 
 
 87. The results of the experiments made at Essen in 1889 
 have been published in the ' Kevue d'Artillerie,' vol. xxxv. 
 These experiments were made with Nobel's powder fired from 
 four different guns, the details of which are given in the 
 following Table, No. I. 
 
 TABLE I. 
 
 
 Number of Gun. 
 
 I. 
 
 II. 
 
 III. 
 
 IV. 
 
 3-287 
 40 
 2310 
 2-20 
 to 
 3-54 
 15-5 
 to 
 17-84 
 
 Calibre in inches 
 Length of gun in calibres 
 \Veight of gun Ibs 
 
 1-968 
 40 
 490 
 ( 0-66 
 to 
 0-80 
 3-81 
 to 
 4-10 
 
 2-362 
 40 
 862 
 0-66 
 to 
 1-21 
 6-84 
 to 
 6-86 
 
 2-984 
 28 
 904 
 0-66 
 to 
 1-17 
 
 I- 
 
 of charge 
 of projectile .. .. 
 
 From the results obtained at Essen the following Tables 
 II. and III. have been constructed. 
 
 Table II. gives the value of the coefficients A and B of 
 formula (1) and (2) ( 35). 
 
 Table III. gives the velocities and pressures, calculated 
 
12 
 
 SMOKELESS POWDER. 
 
 with these coefficients employed in formulae (1) and (2), and 
 compared with the results actually obtained at Essen. 
 
 TABLE II. 
 
 No. of 
 Gun. 
 
 Number 
 of Rounds 
 Fired. 
 
 Size of 
 Grain of 
 Powder. 
 
 Weight of 
 Charge. 
 
 Weight of 
 Projectile. 
 
 Coefficients. 
 
 A. 
 
 B. 
 
 
 
 in. 
 
 Ibs. 
 
 Ibs. 
 
 
 
 T 
 
 / ^ 
 
 1378 
 
 66 to '80 
 
 3-81 
 
 2560 
 
 20-0 
 
 X* 
 
 I 5 
 
 1181 
 
 66 to -792 
 
 4-10 
 
 2455 
 
 20-5 
 
 
 / 2 
 
 1969 
 
 1 to 1 20 
 
 6-86 
 
 1527 
 
 5-79 
 
 
 
 I 3 
 
 1181 
 
 1 to 1-10 
 
 6-86 
 
 1880 
 
 10-20 
 
 III. 
 
 10 
 
 1181 
 
 66 to 1-17 
 
 15 
 
 1429 
 
 10-20 
 
 
 6 
 
 1969 
 
 2-2 to 3-74 
 
 15-5 
 
 879 
 
 0-885 
 
 TV 
 
 4 
 
 1557 
 
 3-3 to 3-54 
 
 17-84 
 
 920 
 
 1-215 
 
 J. V 
 
 2 
 
 1181 
 
 3-3 
 
 17-84 
 
 911 
 
 1-215 
 
 
 2 
 
 1181 
 
 3-286 
 
 17-84 
 
 986 
 
 1-760 
 
 TABLE III. 
 
 No. of 
 Gun. 
 
 Eound . . 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 
 VELOCITY Feet per 
 
 Second. 
 
 
 
 
 f Observed 
 
 1886 
 
 2089 
 
 2171 
 
 1798 
 
 2014 
 
 2070 
 
 
 
 . 
 
 [Calculated 
 
 1887 
 
 2104 
 
 2165 
 
 1797 
 
 2018 
 
 2077 
 
 
 
 
 / Observed 
 
 1637 
 
 1758 
 
 1109 
 
 1860 
 
 2043 
 
 
 
 
 . 
 
 [Calculated 
 
 1640 
 
 1761 
 
 1109 
 
 1890 
 
 2019 
 
 
 
 
 
 /Observed 
 
 1086 
 
 1188 
 
 1283 
 
 1417 
 
 1517 
 
 1591 
 
 
 
 . 
 
 (Calculated 
 
 1047 
 
 1174 
 
 1284 
 
 1429 
 
 1535 
 
 1607 
 
 
 
 TV 
 
 | Observed 
 
 1607 
 
 1883 
 
 2004 
 
 2136 
 
 2234 
 
 2336 
 
 2231 
 
 2168 
 
 JL V . 
 
 (Calculated 
 
 1588 
 
 1821 
 
 2044 
 
 2151 
 
 2259 
 
 2364 
 
 2231 
 
 2166 
 
 
 PRESSURES Tons per Square Inch. 
 
 
 /Observed 
 
 8'46 
 
 8-96 
 
 13-23 
 
 9-72 11-33 
 
 13-03 
 
 
 
 I. 
 
 (Calculated 
 
 8-71 
 
 11-83 
 
 12-80 
 
 8-94 12-16 
 
 13-12 
 
 
 
 
 ("Observed 
 
 6-89 
 
 8-60 
 
 3-12 
 
 jf 
 
 10-18 
 
 12-48 
 
 
 
 II. 
 
 (Calculated 
 
 7-00 
 
 8-47 
 
 3-10 
 
 55 
 
 10-20 
 
 12-34 
 
 
 
 
 /Observed 
 
 5-76 
 
 7-08 
 
 8-60 
 
 10-50 
 
 12-35 
 
 13-36 
 
 
 
 III. 
 
 (Calculated 
 
 4-44 
 
 6-65 
 
 7-90 
 
 10-20 
 
 11-77 
 
 13-96 
 
 
 
 
 /Observed 
 
 5-33 
 
 8-43 
 
 9-02 
 
 9-25 
 
 11-20 
 
 11-69 
 
 13-24 
 
 14-35 
 
 IV. 
 
 (Calculated 
 
 4-28 
 
 6-17 
 
 8-41 
 
 9-63 
 
 10-96 
 
 12-30 
 
 13-23 
 
 14-40 
 
 French Experiments. 
 
 38. The experiments made with the French smokeless 
 powder B.N. were made with two of Canet's quick firing 
 guns of (10 cm.) 3 '937 inch and (15 cm.) 5 '905 inch calibre, 
 each of 48 calibres in length. 
 
SMOKELESS POWDER. 
 
 13 
 
 This is the total length of gun over all, the length of 
 travel of the projectile being about 38 calibres. 
 
 The powders used were all of the description called B.N. 
 In the 3-937 inch gun, three different lots were used, which 
 may account for the difference of the coefficients A and B, 
 whilst in the 5 905 inch gun the powder was of the same 
 brand throughout. 
 
 39. Table IV. gives the values of A -and B, and Table V. 
 the comparison of the observed with the calculated ballistic 
 results, corresponding with Tables II. and III. for the Nobel 
 powder. 
 
 TABLE IV. 
 
 Gun 
 
 Calibre. 
 
 Number 
 of Rounds 
 Fired. 
 
 Size of 
 Grain 
 unknown. 
 
 Weight of 
 Charge. 
 
 Weight of 
 Projectile. 
 
 Coefficients. 
 
 A. 
 
 B. 
 
 in. 
 
 
 
 Ibs. 
 
 Ibs. 
 
 
 
 3-937 
 
 6 
 
 Lot 1 
 
 5-28 to 8-58 
 
 28-6 
 
 526 
 
 2314 
 
 
 4 
 
 Lot 2 
 
 7-93 to 8-16 
 
 28-6 
 
 526 
 
 2807 
 
 
 5 
 
 Lot 3 
 
 7-93 to 9-92 
 
 28-6 
 
 470 
 
 1847 
 
 5-905 
 
 9 
 
 Lot 4 
 
 17-64 to 33-08 
 
 89-0 
 
 198 
 
 0172 
 
 TABLE V. 
 
 Gun. 
 
 Round . . 
 
 1 
 
 2 
 
 3 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 
 
 
 j j 
 
 
 
 ins. 
 
 
 
 VELOCITY feet per second. 
 
 3-937 
 
 /Observed 
 
 1834 
 
 2001 
 
 2238 
 
 2434 
 
 2562 
 
 2628 
 
 
 
 
 Lot 1 
 
 (Calculated 
 
 1829 
 
 2057 
 
 2273 
 
 2431 
 
 2586 
 
 2637 
 
 
 
 
 3-937 
 
 /Observed 
 
 2490 
 
 2555 
 
 2582 
 
 2559 
 
 
 
 
 
 
 Lot 2 
 
 \Calculated 
 
 2482 
 
 2574 
 
 2591 
 
 2540 
 
 
 
 
 
 
 3-937 
 
 /Observed 
 
 2237 
 
 2355 
 
 2536 
 
 2615 
 
 2605 
 
 
 
 
 
 Lot 3 
 
 {Calculated 
 
 2221 
 
 2405 
 
 2539 
 
 2627 
 
 2627 
 
 
 
 
 
 5.Qf)fj 
 
 /Observed 
 
 1666 
 
 1962 
 
 2303 
 
 2428 
 
 2603 
 
 2674 
 
 2671 2750 
 
 2746 
 
 J7l/cl 
 
 (Calculated 
 
 1716 
 
 2008 
 
 2325 
 
 2470 
 
 2611 
 
 2680 
 
 2680,2750 
 
 2750 
 
 
 PRESSURES tons per square inch. 
 
 3-937 
 
 /Observed 
 
 6-54 
 
 8-79 
 
 11-34 
 
 14-20 
 
 15-88 
 
 16-83 
 
 
 
 
 Lotl 
 
 (Calculated 
 
 6-45 
 
 8-78 
 
 11-47 
 
 13-72 
 
 16-17 
 
 17-04 
 
 
 
 
 3-937 
 
 /Observed 
 
 17-65 
 
 17-97 
 
 19-62 
 
 18-16 
 
 
 
 
 
 
 Lot 2 
 
 (Calculated 
 
 17-65 
 
 19-47 
 
 19-71 
 
 18-73 
 
 
 
 
 
 
 3-937 
 
 /Observed 
 
 11-75 
 
 13-50 
 
 16-64 
 
 18-10 
 
 
 
 
 
 
 Lot 3 
 
 (Calculated 
 
 11-62 
 
 14-37 
 
 16-60 
 
 18-17 
 
 
 
 
 
 
 
 /Observed 
 
 4-13 
 
 6-22 
 
 11-77 
 
 13-66 
 
 16-76 
 
 16-83 
 
 17-34 
 
 18-41 
 
 18-54 
 
 5-905 
 
 (Calculated 
 
 4-83 
 
 8-36 
 
 12-00 
 
 14-18 
 
 16-38 
 
 17-56 
 
 17-56 
 
 18-81 
 
 18-81 
 
 
 
14 SMOKELESS POWDER. 
 
 40. From these tables it appears that the formulae (1) and 
 (2), above given, represent very closely the results obtained 
 by experiments, and it is therefore probable that the indices 
 75 and 2 denote the relations between the weight of the 
 charge and the velocity and pressure respectively, at any rate 
 it is so in these guns. 
 
 41. A comparison may be made between the French B.N. 
 and the Nobel powder, first as regards the energy of the 
 projectile per Ib. of powder, and second as regards the energy 
 per ton weight of gun. 
 
 For this purpose take the (10 cm.) 3 '937 inch Canet gun, 
 weighing 4620 Ibs., and compare it with the 3*287 inch 
 Krupp gun, weighing 2310 Ibs. ; the Canet gun being fired 
 with B.N., and the Krupp gun with Nobel's powder of 1557 
 inch size of grain. 
 
 It is assumed that the strain on the two guns is the same, 
 that is to say, that the charge shall be such as will give the 
 same maximum pressure in the two guns, and that this 
 pressure shall be 18 '17 tons per square inch, as in the fourth 
 round of this gun in Table V., giving a velocity of 2615 foot- 
 seconds. 
 
 Therefore, in the Canet gun, 
 
 which gives 
 
 Energy per ton of gun 657*1 foot-tons, 
 per Ib. of powder 136*7 foot-tons. 
 
 42. In the 3*257 inch Krupp gun, in order to give the 
 pressure of 18* 17 tons, the weight of charge of the * 1557 inch 
 grain Nobel powder is found by the equation P = 1 215 w 2 , 
 whence 
 
 and the velocity with this charge would be 
 
 V = 920 w" 75 = 2537 feet per second; 
 
SMOKELESS POWDEE. 
 
 15 
 
 therefore 
 
 which gives 
 
 foot-to,,, 
 
 Energy per ton of gun = 771 7 foot-tons. 
 per Ib. of powder = 205 8 
 
 43. If the powder of 0*1969 inch grain were used, the 
 requisite weight of charge would be 4*531 Ibs., and the 
 velocity 2730 feet per second, giving the Energy of the 
 15 Ib. projectile = 774*7 foot-tons, which gives 
 
 Energy per ton of gun = 751*2 foot- tons. 
 per Ib. of powder = 171 
 
 44. These results are brought together for comparison in 
 the following Table. 
 
 TABLE VI. 
 
 
 3-937 inch Gun. 
 B.N. Powder. 
 
 3-287 inch Gun. 
 1557 inch 
 Nobel. 
 
 3 -287 inch Gun. 
 1969 inch 
 Nobel. 
 
 Total energy 
 Energy per ton of gun 
 Energy per Ib. of powder . . 
 
 1355 
 657-1 
 136-7 
 
 795-8 
 771-7 
 205-8 
 
 774-7 
 751-2 
 171-0 
 
 45. The results show somewhat in favour of the Nobel 
 powder, both per ton of gun and per pound of powder. 
 
 46. It must further be observed that the 3 937 inch gun 
 has the advantage over the 3 287 inch gun, in being a gun of 
 48 calibres as against 40 calibres in the latter. If the guns 
 had been what is termed " similar guns " and similarly 
 loaded, the velocities would have been the same, but the 
 weight of projectiles as the cubes of the calibres, con- 
 sequently the energy of similar guns increases as the cube of 
 the calibre, which in the present case is in the ratio 
 
 '3-937\3 
 
 ,3-287; 
 
 1-719. 
 
16 SMOKELESS POWDER. 
 
 Consequently, had the guns been similar and similarly 
 loaded, the total energy would have been 
 
 as 1355 : 788-5; 
 
 so that not only is the energy of the smaller gun greater than 
 the due proportion, but this is the case under the disadvantage 
 of being the shorter gun. 
 
 47. So far then as these experiments go, it appears that 
 the Nobel powder is superior in ballistic power to the B.N. 
 powder. 
 
SMOKELESS POWDER. 17 
 
 IV. 
 
 PRESSURES IN THE CHASE WITH NEW POWDER COMPARISON 
 WITH PRESSURES PROM PEBBLE POWDER. 
 
 48. In the absence of further experimental' data it is 
 impossible to deduce the relations between the velocity and 
 pressure and the other ballistic elements, such as the length 
 of travel of projectile, weight of projectile, and calibre of the 
 gun, so that the coefficients A and B given above can only 
 be made use of for " similar " guns. 
 
 49. It is very important to ascertain as far as may be 
 possible, the distribution of pressures along the chase whilst 
 the projectile is travelling to the muzzle. 
 
 50. As has already been shown, there is reason to believe 
 that in a close vessel impermeable to heat, the pressure from 
 the new powder would be about double of that given by the 
 old black powder. Consequently, as in practice the maximum 
 pressure is not greater, it follows that the rate of combustion 
 must be slower, thus giving more time for the projectile to 
 get out of the way, and by thus increasing the space, keep 
 down the pressure. 
 
 It is also quite possible that the combustion may go on for 
 a considerable time after the maximum pressure is attained, 
 and that thus the pressures towards the muzzle may be 
 greater than with the ordinary powders. 
 
 51. As this is a point of great importance relative to 
 the designing of guns, the question requires examination, 
 so far as the limited experience available enables it to be 
 done. 
 
 52. Consider the case of the (15 cm.) 5*905 inch Canet 
 
 c 
 
18 SMOKELESS POWDER. 
 
 Q.F. 15 cm. gun of 48 calibres with B.N. powder, of which 
 the following are the ballistic elements : 
 
 CANET'S Q.F. 15 CM. GUN. 
 
 Calibre of gun ........ 5*905 inches. 
 
 Length of travel of projectile .. 224*5 
 
 Equivalent length of chamber .. 53 
 
 Capacity of chamber ...... 1500 cubic inches. 
 
 of chase ........ 6174 
 
 Total capacity of gun ...... 7674 
 
 rr/trr j 
 
 Number cf expansions Z- = 5*116 
 1500 
 
 Weight of charge ........ 33*08 Ibs. 
 
 Weight of projectile .. .. .. 89 
 
 Weight of gun ........ 6*29 tons. 
 
 Muzzle velocity ........ 2750 f.s. 
 
 Total energy = 4665 foot-tons. 
 
 Energy per ton of gun ...... 744' 6 
 
 per Ib. powder ...... 141*0 , 
 
 Maximum pressure ...... 18*81 tons per sq. in. 
 
 53. First, it may be asked, what must have been the mean 
 pressure in the gun ? The total energy expended on the 
 projectile was 4665 foot-tons, to which must be added that 
 expended in overcoming friction and expelling the gases, &c. 
 This may be estimated at an additional 20 per cent, making 
 the total energy 5598 foot-tons. 
 
 Now the area of section of the projectile is 27*4 inches, and 
 the travel 18*4 feet. Therefore, if p be the mean pressure, 
 
 p = -- -- - = 10*92 tons per square inch. 
 
 54. Next, if it be granted that the pressure in a close 
 vessel would be 78 * 53 tons per square inch, and that the pro- 
 ducts of combustion act as a perfect gas, it may be inquired, 
 at what point in the travel of the projectile will the pressure 
 be reduced to the maximum pressure of 18 * 81 tons ? This 
 can only be approximately ascertained in the absence of 
 
SMOKELESS POWDEE. 19 
 
 knowledge as to the loss of heat due to cooling, but from the 
 considerations set forth in ' Internal Ballistics/ Chapter V., 
 it would appear that this is not very great. Leaving this 
 
 loss out of account, there is the relation ^ = ( ) , where 
 
 p W 
 
 PO and V Q are the original and p and v the final pressures and 
 volumes, and as the volumes are proportional to the lengths, 
 
 the relation becomes = (= ) . Now let 1 Q be the length 
 
 of the bore which would be occupied by the charge at 
 gravimetric density = 1, and I the distance from the breech 
 at which the pressure is reduced to p = 18 '81, then 
 
 4i9 
 
 55. For ordinary powder the space occupied at gravimetric 
 density = 1, is 27 7 cubic inches per Ib. or 1 decimetre cube 
 per kilogramme, and when the charge is thus spaced it is said 
 to be of gravimetric density equal unity. If, however, the 
 space be any other number, say 30 inches to the Ib., the 
 gravimetric density is said to be 
 
 56. It is as well to observe, however, that, with the French, 
 " densite gravimetrique " has a different meaning. 
 
 " Densite gravimetrique "is the weight of 1 cubic deci- 
 metre of powder, not pressed together except by its own weight. 
 Consequently it is evident that the " densite gravimetrique " of 
 a given powder is dependent partly on its absolute density, 
 i. e. specific gravity, and partly on the size of the grain. For 
 instance, the French powder F x has an absolute density of 
 1 * 750, whilst its gravimetric density is 830 to 870, whilst 
 the WJij-, which has nearly the same absolute density, has a 
 gravimetric density of 1 03 to 1 17. 
 
 The equivalent of " gravimetric density " in French is not 
 " densite gravimetrique," but '* densite de chargement." 
 
 c 2 
 
20 SMOKELESS POWDER. 
 
 57. As is well known, with the ordinary old powders 27 7 
 cubic inches is the space occupied by 1 Ib. of powder. But 
 this is not so with the new powder. With respect to this there 
 is much reticence. It is, however, probable that 1 Ib. of this 
 powder may occupy about 31 cubic inches of space, and it is 
 on this assumption that the following remarks are made. 
 Though the conclusions arrived at may not be quite 
 correct, yet they will be relatively so, and will therefore be 
 useful in the examination of the ballistic properties of the 
 new powder. 
 
 58. Assuming, then, that the space occupied by 1 Ib. of 
 powder is 31 inches, the length of bore 1 Q occupied by the 
 charge is easily determined. 
 
 The charge being 33*08 Ibs., and the area of the bore 
 27 4 inches, we get 
 
 _ 33-08 x 31 Q _ . 
 Length = = 37-42 inches. 
 
 59. Let, then, A D (Fig. 1) represent the bore of the gun* 
 A B the " equivalent length " of the chamber, that is to say, 
 a length of bore whose capacity is the same as that of the 
 chamber, and B D the travel of the projectile, and let A A be 
 the length of the bore which would be occupied by the 
 charge at gravimetric density = 1, that is to say, in the 
 present case 37 42 inches. Then, if the powder were fired in 
 a close vessel, the pressure would be 78 53 tons per square 
 inch ; but as the projectile moves away the space increases, 
 and the contest between the evolution of gas and the increas- 
 ing space goes on until a maximum pressure is reached. If 
 it be assumed that all the powder is burnt at this time, the 
 point Ci, on the curve F C x D, corresponding to this maximum 
 pressure, will denote the position of the projectile, and the 
 ordinates between C and D the respective pressures on the 
 bore as the projectile moves to the muzzle ; the curve 
 F G! D being calculated from the formula 
 
 l-319 
 
SMOKELESS POWDER. 
 
 21 
 
 The ordinates between B and C* are indeterminate, and 
 depend upon the rate of evolution of the gas, the weight of 
 projectile and other elements, but it may be assumed that 
 approximately the pressure curve is represented by the curve 
 B G! D! D, and that the point of maximum pressure is at C 1? 
 
 Tarts 
 SO] 
 
 70- 
 
 60- 
 
 50- 
 
 40- 
 
 JO 
 
 20- 
 
 S F 
 
 1 18 -53 torus 
 
 FIG. 1. 
 
 and that the total work done on the projectile is represented 
 by the area of the curve multiplied by the area of the bore 
 of the gun. 
 
 60. Taking the unit for abscissa in feet, and for the ordinate 
 in tons per square inch, the area of the curves A GI D t D is 
 found to be 210*2, which is the foot-tons per square inch of 
 
 * The assumption that the curve from B to C t is one-fourth of an ellipse 
 has been found by the author to give very satisfactory results. 
 
22 
 
 SMOKELESS POWDER. 
 
 bore; and multiplying this by 27*4 the area of the bore 
 gives 5761 foot-tons. If from this be deducted 20 per cent, 
 for the resistance, friction, and expulsion of the gases, there 
 remains 4629 foot-tons for the energy of the projectile. 
 
 This was found by experiment to be 4665 foot-tons. 
 
 It may therefore be concluded that the pressure curve 
 (Fig. 1) represents, approximately, the pressure in the gun 
 with a 33 Ib. charge of the new powder. 
 
 61. Let now this be compared with the corresponding 
 diagram of the same gun fired with a full charge of pebble 
 powder. 
 
 The capacity of the chamber being 1500 cubic inches, the 
 1500 
 
 full charge will be 
 Appendix C, gives 
 
 27-7 
 
 Muzzle velocity .. 
 Pressure on projectile 
 
 = 54 Ibs., which, as is shown in 
 
 2570 feet per sec. 
 22 -00 tons. 
 
 Therefore the energy is 
 2570 2 x 89 
 
 x 2240 
 
 = 4073 foot-tons, 
 
 which gives 
 
 Energy per ton of gun 
 per Ib. of powder . . 
 
 650 -2 foot-tons. 
 75-43 
 
 62. The following Table shows the comparison between 
 the B.N. and pebble powders in the 5 * 90 inch gun. 
 
 Powder. 
 
 Weight 
 of 
 Charge. 
 
 Weight 
 of 
 Projectile. 
 
 Muzzle 
 Velocity. 
 
 Maximum 
 Pressure 
 on 
 Projectile. 
 
 Total 
 Energy. 
 
 Energy. 
 
 Per Ton of 
 Gun. 
 
 Per Lb. of 
 Powder. 
 
 
 Ibs 
 
 Ibs 
 
 feet per 
 
 tons per 
 
 foot- 
 
 
 
 
 
 
 second. 
 
 sq. in. 
 
 tons. 
 
 
 
 B.N. 
 
 33-08 
 
 89 
 
 2750 
 
 18-81 
 
 4665 
 
 744-6 
 
 141-0 
 
 Pebble.. 
 
 54-00 
 
 89 
 
 2570 
 
 22-0 
 
 4073 
 
 650-2 
 
 75*43 
 
SMOKELESS POWDEE. 
 
 23 
 
 63. If a pressure curve be constructed for the pebble 
 powder in the same manner as above described, and super- 
 imposed upon the curve for the charge of 33 08 Ibs. of B.N. 
 as in Fig. 2, the difference in the distribution of pressure is 
 very strikingly seen. 
 
 FIG. 2. 
 
 64. The maximum pressure on the base of the projectile 
 is 18 * 81 tons per square inch with the B.N., and 22 tons with 
 the pebble powder, but the position at which it attains its 
 maximum is when the shot has travelled 59 inches in the 
 first case, against 16 inches in the second. 
 
 Again, the final pressure is 5 65 tons per square inch with 
 the B.N., against 3 1 tons with the pebble powder. 
 
24 SMOKELESS POWDER. 
 
 V. 
 
 EFFECT OF THE NEW POWDER ON EXISTING GUNS. 
 
 65. Enough has now been said to show that the new 
 powder is a revolutionary element in ballistic practice, and 
 that it must consequently exert a corresponding influence 
 on gun construction. 
 
 66. It is therefore very important to examine what will be 
 the effect of using such powder in the present new type steel 
 guns, which were designed for the older powders, such as the 
 black and brown prismatic, and the still later E.X.E. powder. 
 
 67. These powders are characteristically weak powders, 
 that is to say, they burn slowly and give low pressures in 
 guns. The effect is made up by largely increasing the 
 charges, and in order to give time for the entire combustion 
 and also for utilising the expansive force of the gases, the 
 guns are made very long. 
 
 In order to contain the large charges and also to reduce 
 the length of the gun, enlarged powder chambers are 
 adopted, with, however, the disadvantage of increasing the 
 size of the breech mechanism, and the strain upon it. 
 
 68. Now, in the first place, it may be asked what will be 
 the effect of using the new powders on these guns ? It is 
 claimed for the new powders that, in addition to their quality 
 of smokelessness, they will give vastly higher ballistic 
 results, while they will strain the gun less owing to their 
 low maximum pressure, and this statement has been used 
 as an argument against the necessity of adopting wire 
 guns, instead of the usual forged steel construction. 
 
 68a. It is not intended to enter here into the questions of 
 the relative cost of production, the greater freedom from 
 
SMOKELESS POWDER. 25 
 
 latent defects, the quicker production, or the relative facilities 
 of repairs, in all which respects the wire system has 
 undoubted advantages. But it is desired to show that, if 
 the full advantage is to be obtained from the high ballistic 
 properties of the new powder, it can only be obtained by the 
 use of comparatively high pressure, and consequently, very 
 strong guns, such as can only be produced by the wire system 
 of construction. 
 
 69. It is argued that the advantages of the new powders 
 may be utilised in two ways. 
 
 70. Either by retaining the present initial velocity with 
 the benefit of a great reduction of pressure, or on the other 
 hand by retaining the present maximum pressure of about 
 16 tons per square inch, and thus obtaining a very great 
 increase of velocity, although admittedly retaining the 
 disadvantage of a great length of gun. 
 
 71. The former alternative is thought to be the better 
 for field guns, as they cannot be lengthened without increase 
 of weight, which is inadmissible. Morever, the weight of 
 cartridges could thus be reduced, consequently more of them 
 could be carried ; whilst it has also been said that, as the 
 pressures are reduced, the strain on the gun carriage would 
 be relieved. 
 
 72. This last assertion is, however, a mistake. The effect of 
 the strain on the carriage is proportional to the work done 
 on it, and this varies as the square of the velocity of recoil, 
 which velocity, cseteris paribus, is in proportion to the 
 velocity of the projectile, and has nothing to do with the 
 pressure by which that velocity is created. 
 
 Consequently, if the muzzle velocity be unchanged the 
 strain on the carriage must be the same, and if, by the use 
 of the new powder, the velocity be increased, the strain on the 
 carriage must be increased correspondingly. 
 
 73. This is of course slightly modified by the fact that, in 
 calculating the velocity of recoil, a portion of the weight of 
 the charge must be taken into account, as well as the weight 
 of the projectile, but the effect of this will be comparatively 
 
26 SMOKELESS POWDER. 
 
 small, and in the case of increased velocity of the projectile, 
 will be far less than the increase due to the increased 
 velocity of the projectile, which is not a function of the 
 maximum pressure, but depends on the mean pressure, which 
 is quite another thing. 
 
 74. As regards the length of gun required for the new 
 powder, it is argued that by increasing the pressure it would 
 be necessary also to increase the length of the gun to a 
 practically impossible extent. 
 
 75. But this also is erroneous, for it apparently rests on 
 the assumption that the maximum pressure can only be 
 increased by increasing the weight of charge, and that unless 
 the length of the chase be correspondingly increased, part 
 of the charge will be blown out of the muzzle unburnt. 
 
 76. Now the maximum pressure depends, not altogether, 
 nor indeed principally, on the weight of the charge, but is 
 chiefly affected by the rate of evolution of the gas, which 
 is regulated almost ad libitum by modifying the form and 
 size of the grain. 
 
 It is therefore quite practicable to increase the maxi- 
 mum pressure, even if the weight of charge be diminished. 
 
 77. This will be the more evident after the following 
 examination of the action of the powder in a gun. 
 
 78. In the first place, reverting to Fig. 2 which shows 
 the pressure in the same gun when fired with charges of 
 33*08 B.N. and 54 Ibs. P respectively; in order to complete 
 the curves the pressures behind the points of the maximum 
 must be indicated. 
 
 79. According to M. Sarrau's formulae for ordinary powder, 
 if P be the pressure on the breech, P the maximum 
 pressure on the base of the projectile, making use of Eng- 
 lish unities of pounds for weight and tons per square inch 
 for pressure, 
 
 w and W being the respective weights of charge and projectile. 
 
SMOKELESS POWDEE. 27 
 
 Another formula which is said to give better results, 
 especially with slow powders, is 
 
 _ P 
 " 
 
 80. Making use of this latter formula and the weights 
 corresponding to Fig. 2, we find 
 
 For B.N. powder P = P 1^ = 1 19 P. 
 
 Oi7 
 
 For pebble P = P = 1-30 P. 
 
 by 
 
 From which the breech pressures corresponding to the 
 maxima in the diagrams are 22 -38 and 28 -6 tons respec- 
 tively. 
 
 Setting off these ordinates at the breech the line C^ 
 represents the internal pressure in the gun when the pro- 
 jectile is at Cj, and a line parallel to it, such as g g^ represents 
 the pressure when the projectile is at any other part g. 
 
 81. What is most important to note is that whilst the 
 maximum pressure is considerably less with the B.N. powder, 
 although the work done is nearly 15 per cent, more, and 
 the powder charges 40 per cent, less, the pressures are 
 thrown so much further forward, that the B.N. powder if 
 fully utilised will require a very differently proportioned 
 gun, one, namely, in which there is about the same strength 
 behind the point of maximum pressure, but very much 
 greater strength in front of it. 
 
 82. Taking for instance the point g lt Fig. 2, at 110 inches 
 from the muzzle, the pressure to be resisted will be 10 tons 
 per square inch with the B.K powder, as against 5 J tons with 
 the pebble. 
 
 83. It is quite true that this pressure may be reduced by 
 reducing the charge of the B.N. powder. 
 
 84. If, instead of firing with 33 * 08 Ibs., the charge was 
 reduced to 28 f 52 Ibs., the velocity would be the same as 
 that given by the 54 Ibs. of pebble powder, and the maximum 
 
28 
 
 SMOKELESS POWDEE. 
 
 pressure would be reduced to 14 tons per square inch. The 
 length of charge would be 30 inches of the bore. 
 
 85. The dotted curve, Fig. 3, is constructed from these 
 data, and being superimposed on the diagram for 54 Ibs. of 
 pebble powder, shows the respective action of the two 
 
 FIG. 3. 
 
 28 54 B.N 
 54-CC P 
 
 -53 ; 
 
 224-- 5 - 
 
 powders in the same gun, while producing the same ballistic 
 effects. 
 
 86. It is evident that a gun designed to sustain the 
 pressures of the pebble powder is insufficient in strength to 
 sustain the pressures of the new powder in all that part of 
 the chase commencing at about 180 inches from the 
 muzzle. 
 
 87. To elucidate this, let an examination be made of the 
 Eoyal Gun Factory 6 a B.L. gun, MAKK IV. of the follow- 
 ing ballistic elements : 
 
 Calibre 
 
 Length of rifling .. 
 Capacity of chamber 
 Equivalent length of ditto 
 Total capacity of gun .. 
 
 Expansions 
 
 Charge E.X.E 
 
 Weight of projectile 
 Muzzle velocity 
 Maximum pressure 
 
 6 inches. 
 127 
 
 1364 cube inches. 
 47-03 inches. 
 5105 cube inches. 
 3-743. 
 48 Ibs. 
 100. 
 
 1980 feet per second. 
 16 % 50 tons per sq. in. 
 
SMOKELESS POWDEE. 
 
 29 
 
 88. In order to compare this gun with the 15 cm. Canet 
 gun, it must first be considered on the supposition that it is 
 lengthened so as to make the travel of the shot the same, 
 viz. 224*5 inches, and then determined what would be the 
 muzzle velocity with the same charge of 48 Ibs. of E.X.E. 
 powder but with a projectile of 89 Ibs. 
 
 89. From such data as are at the author's disposal it 
 appears that the " characteristics " of the E.X.E. powder 
 
 are 
 
 Log a = -06136 
 Log/3 = - 1-47844 
 
 Making use of which in Sarrau's binomial formulae for 
 
 velocity gives 
 
 V = 2444 feet per second. 
 
 90. This is the velocity which is taken as a basis of com- 
 parison with the Canet gun fired with B.N. powder. 
 
 Now, by formula (1) 
 
 V = 198 to*, 
 
 and making V = 2441 gives 
 
 w = 28 -52 Ibs. 
 
 Then by formula (2) 
 
 P = -0172w; 2 , 
 which making w = 28 52 gives 
 
 P = 14 tons per sq. inch 
 
 for the Canet gun. 
 
 The comparison is therefore as follows : 
 
 
 Charge. 
 
 Projectile. 
 
 Muzzle 
 Velocity. 
 
 Maximum 
 Pressure. 
 
 
 Ibs. 
 
 Ibs. 
 
 feet per 
 second. 
 
 tons. 
 
 Canet 15 cm. gun .. 
 
 28 -52 B.N. 
 
 89 
 
 2444 
 
 14 
 
 R.G.F. 6 in. Mark IV.) 
 lengthened / 
 
 48 E.X.E. 
 
 89 
 
 2444 
 
 16-5 
 
30 
 
 SMOKELESS POWDER. 
 
 Thus, with 2J tons less pressure the Canet gun only 
 requires about T 7 ^ of the charge required of E.X.E. 
 
 91. It remains, however, to be seen how the variations of 
 pressure throughout the chase take place in the two guns, 
 and for this purpose recourse must be had to pressure curves, 
 obtained as above described. These, though not accurately 
 correct, represent approximately the real pressures. The 
 curve for the E.X.E. powder is obtained by making use of 
 the formula given in 'Internal Ballistics,' page 172, with 
 
 FIG. 4. 
 
 allowance of 20 per cent, for resistance, and is represented by 
 the full line in Fig. 4. 
 
 92. The curve for the B.N. powder is obtained as follows : 
 The charge of 28-5 Ibs. at gravimetric density = 1 would 
 occupy 28-5 x 31 = 883 cubic inches, which is equal to 
 30 inches of- the bore, and the initial pressure in this space 
 would be 78-52 tons per square inch. Therefore the equa- 
 tion to the curve is 
 
 /30 
 
 = 78-52 
 
 from which the curve represented by the dotted line, Fig. 4, 
 is constructed. 
 
 Placing the two curves over each other, as shown in the 
 
SMOKELESS POWDEE. 31 
 
 figure, it is seen that, although the maximum pressure of the 
 B.N. powder is 3 tons less than that of the E.X.E., yet it is 
 thrown about 39 inches further forward, and that at this 
 point the pressure is about 4 tons per square inch greater 
 than it is with the E.X.E. at the same point in the gun. 
 
 93. To pass from this to the Mark IV. gun of the actual 
 length, it is sufficient to cut off from the diagram the excess 
 of length in front of A ; the length up to A being that of 
 the travel of the shot with Mark IV. gun, viz. 127 inches. 
 Then, by subtracting the areas A A! G! C and A A 2 C 2 C from 
 the original areas of the two curves, the remaining areas 
 represent the work done in the two guns if reduced to the 
 length of the actual Mark IV. gun. 
 
 The original areas are 4537 for each, and the deductions 
 1299 and 1032; therefore the remaining areas are 3238 and 
 3505 respectively, representing the energies of the two guns 
 corresponding to muzzle velocities of 2049 and 2132 feet 
 per second. 
 
 94. From this it follows that with the E.G.F. 6-inch 
 Mark IV. gun and a projectile of 89 Ibs. nearly the same 
 velocity would be obtained from 28^ Ibs. of B.N. as from 
 48 Ibs. of E.X.E., and that with 3 tons per square inch less 
 maximum pressure. But this maximum would be about 
 39 inches nearer the muzzle. 
 
 95. Let it now be inquired how the new distribution of 
 pressure would affect the Mark IV. gun ? 
 
 It may be assumed that this gun has no superfluous 
 strength, especially in front of the trunnions ; indeed, 
 evidence is not wanting to show that the strength of existing 
 guns is deficient rather than excessive in this respect. 
 
 But let it be assumed that the present strength is suitable 
 for the pressures developed by a full charge of 48 Ibs. E.X.E. 
 powder. 
 
 96. Let the strength of the gun be examined at two points, 
 one at 64 inches, the other at 32 inches from the muzzle. 
 At the first point the gun consists of the A tube 1 75 inch 
 thick, and the B l tube 1 '385 inch thick. 
 
 , 
 
32 SMOKELESS POWDER. 
 
 At the second point it consists of the A tube, 1 * 35 inch 
 thick, and the BX tube, 1'25 inch thick. 
 
 97. According to the principles laid down in the Official 
 Treatise on the Manufacture of Ordnance, 1886, no gun is 
 allowed to be strained beyond three-fourths of the elastic 
 limit of the material, which is fixed at 15 tons per square 
 inch for the A tube, and 18 tons for hoops or the 
 B tube. 
 
 Consequently the allowed strain is 15 x = 11 '25 tons 
 for the A tube, and 18 x f = 13 '50 tons for the B tube. 
 
 98. Making use of the above dimensions, it will be found by 
 the usual formula that the greatest permissible pressure is 
 9 665 tons per square inch at 64 inches from muzzle, and 
 6 983 tons per square inch at 32 inches from muzzle. 
 
 99. Now, with the E.X.E. powder the pressures at these 
 points are about 10 tons and 8 tons^per square inch respec- 
 tively, so that the gun nearly answers to the required condi- 
 tions; but with the B.N. powder the pressures would be 
 14 tons and 10 tons per square inch respectively, an excess 
 of 4 tons in the first case and about 3 tons in the second. 
 
 100. It is therefore manifest that the strength of this gun 
 in the chase is quite insufficient for a charge of 28 f 52 Ibs. of 
 B.N. powder, and any less charge would give a less ballistic 
 result. 
 
 101. It may be objected that the dotted curve Fig. 4 is 
 theoretical, and not based on actual observation, except as 
 regards the maximum pressure, and that the actual results 
 of firing have not shown the guns to be too weak. 
 
 102. With regard to the last objection, it has not much 
 weight. A gun may go on firing for a greater or less time 
 without bursting or any visible damage, but not the less 
 surely is it injured every time that it is strained beyond the 
 elastic limit, and this seems to be fully admitted at Woolwich, 
 where, as stated in the Official Treatise, the practice is to 
 limit the maximum strain to three-fourths of the elastic 
 limit. If, therefore, the present guns are not too strong for 
 the present powder, and if the pressure curves be even 
 
SMOKELESS POWDER. 33 
 
 approximately correct, the guns cannot safely be used with 
 the new powder with increased ballistic effect. 
 
 103. The objection against the curve as theoretical carries 
 more weight. Not only is it theoretical, but it depends 
 on the assumption of the pressure in a close vessel being 
 78 * 52 tons per square inch. 
 
 The reason for this assumption is given above, and there is 
 nothing in it which appears either improbable or inconsistent 
 with such other facts as are known with respect to this 
 powder. 
 
 The law of decrease of pressure by which the ordinates and 
 the curves are calculated is a rational law, and in all pro- 
 bability approximately true for the powder gases. 
 
 104. Moreover, the velocities deduced from the area of 
 these curves (due allowance being made for other resist- 
 ances) agree very well with the observed velocities, and 
 consequently, whatever be the real form of the pressure 
 curve, its area must be approximately the same as that of the 
 dotted curve, Fig. 4. 
 
 105. In the next place, the final ordinate at the muzzle 
 must be the same (if all the charge is consumed), but it is 
 quite possible that the point of maximum pressure may be 
 further to the rear than shown in the curve, Fig. 4. 
 
 Indeed, the curve may possibly be of such a form as 
 shown in Fig. 5, A B C, the area of which may be the same 
 as that of A B t C. Even in this case the pressures in front 
 of the chase must be greater than with the other powder. 
 
 It may also be observed that, to permit of the possibility 
 of a curve of the form ABC, the rate of the evolution of 
 gas must be very different from anything previously known. 
 
 106. There is another strain besides the bursting strain 
 which must be provided for, viz. the longitudinal strain in 
 the chase of the gun arising from the friction of the products 
 of combustion rushing along the muzzle. 
 
 107. The importance of this strain has never been recog- 
 nised by gun-makers, nor do there appear to have been any 
 experiments made to ascertain its magnitude. In ' Internal 
 
 D 
 
34 SMOKELESS POWDER. 
 
 Ballistics' reasons have been given for attributing to it a 
 very considerable magnitude, and indeed there can be little 
 doubt on the subject. 
 
 108. To what extent the magnitude of this strain will be 
 affected by the use of the new powder can only be conjec- 
 tured. On the one hand, the volume, pressure, and tem- 
 perature of products of combustion are considerably greater. 
 
 FIG. 5. 
 
 On the other hand, these products consist of nearly perfect 
 gases, and the coefficient of friction will probably be less 
 than in the mixture of gases and finely diffused liquid 
 arising from the combustion of the old powders. 
 
 109. The subject of the longitudinal strain is of such 
 importance that it is inconceivable to the author that gun- 
 makers have taken no steps to ascertain its magnitude and 
 relation to the other ballistic elements. 
 
SMOKELESS POWDER. 35 
 
 VI. 
 
 INFLUENCE OF THE NEW POWDER ON THE DESIGN OF GUNS. 
 
 110. It has been shown that no great improvement in 
 ballistic effect can be looked for, consistent with safety, 
 with the present guns and the new powder. It is, there- 
 fore, proper to give some attention to the subject of a 
 design of gun suitable for the development of the new 
 explosive. 
 
 111. Up to the present, the idea of gun-makers seems to 
 be running in the old groove low pressure and length of 
 gun. 
 
 The French 15 cm. Q.F. Canet gun is called a gun of 
 48 calibres, but that is the length over all. The real length 
 is as follows : 
 
 Chamber 50 inches -f chase 227-5 = 277 -5 inches. 
 
 It is only slightly chambered, and the equivalent length of 
 the chamber is 53 2 inches. The total capacity of the gun 
 is 7674 cubic inches, and of the chamber 1500 cubic inches, 
 so that it is a gun of 5 '116 expansions, that is to say, a very 
 long gun. 
 
 112. But long guns are very inconvenient and objectionable, 
 especially at sea, and the question arises whether it would 
 be practicable to take advantage of the new powder in a 
 short gun, even though it were at the expense of decreasing 
 the efficiency per pound of powder. 
 
 113. The gun may be shortened in two ways : First, by 
 an enlarged powder chamber, which, however, has the dis- 
 
 D 2 
 
36 SMOKELESS POWDER. 
 
 advantage of increasing the strain upon the breech apparatus ; 
 or, secondly, by increasing the maximum working pressure. 
 
 114. To what extent this may be done cannot at present 
 be solved in a general form, inasmuch as the relations be- 
 tween the ballistic effect of the new powder and the ballistic 
 elements, such as calibre of gun, travel and weight of pro- 
 jectile, and " characteristics " of the new powder are unknown 
 in this country. 
 
 115. Recourse must therefore be had to the method of 
 curves, and to such limited information as is given in the 
 published results contained in the first part of this paper. 
 The question will therefore be confined to a gun resembling 
 M. Canet's 15 cm. Q.F. gun with a calibre of 5*95 inches, 
 and travel and weight of projectile 224-5 inches and 
 89 Ibs. 
 
 116. Suppose (what might be easily done) a wire gun to 
 be made so as to give the same margin of safety under a 
 pressure of 30 tons as the Canet gun under a pressure of 
 18-81 tons. 
 
 By the formula (2), P = 0172 w 2 , and making P = 30, we 
 get w = 41 -76 Ibs., and consequently V = 198 wl = 3253 f.s. 
 Let the capacity of the chamber be 45 5 cubic inches per Ib. 
 of powder, which is the same gravimetric density as in the 
 last round of the Canet gun. (See Table II.) 
 
 The capacity of the chamber is 1500 cubic inches, and the 
 equivalent length 53 inches, and the length of charge 
 47 inches. 
 
 With these data the curve Fig. 6 is constructed, the area 
 of which is 301, which multiplied by the area of the pro- 
 jectile 27-4, gives 8247 foot-tons. 
 
 Deducting, as before, 20 per cent for resistances, expulsion 
 of gases, &c., there remains 6595 foot-tons, which corresponds 
 to a velocity of 3271 feet per inch, which is very nearly the 
 velocity found by the formula V = 198 wl. 
 
 117. The weight of this gun would probably be about 
 7J- tons, for on the wire construction it could be made con- 
 siderably lighter in proportion than the Canet gun. 
 
SMOKELESS POWDER. 37 
 
 Therefore the relative efficiency of the two guns would be 
 
 
 
 Energies. 
 
 Description of Gun. 
 
 Energy. 
 
 Per Ton of 
 
 Per Ib. of 
 
 
 
 Gun. 
 
 Powder. 
 
 CanetQ.F 
 
 4665 
 
 744-6 
 
 141 
 
 Proposed gun 
 
 6598 
 
 910-1 
 
 158 
 
 Showing the decided advantage of the high-pressure gun. 
 
 118. It may now be inquired, what would be the length of 
 the proposed high-pressure gun which would have the same 
 ballistic power as the Canet gun ? 
 
 This may be approximately ascertained from the curve 
 Fig. 6. 
 
 The difference of energy imparted to the projectile is 
 1933 foot- tons, to which must be added 20 per cent., making 
 
 FIG. 6. 
 
 30 
 
 10- 
 
 t S3.. 
 
 c 47'- i 
 
 KBH 
 
 41. 76 Ws 
 
 > 102' 
 
 224.5 
 
 2320 foot-tons, which divided by the area 27 * 4, gives 84 68 
 foot-tons to be deducted from the muzzle end of the curve, 
 and since the mean pressure near the muzzle is about 
 10 tons per square inch, the length to be deducted is 
 84-64 
 
 10 
 
 = 8*46 feet or 103 inches, so that the travel of the 
 
 projectile would be 122*5 inches and the total length of the 
 gun over all, about 181 inches instead of 283 inches in the 
 Canet gun. 
 
38. SMOKELESS POWDEE. 
 
 119. The two guns would have the same ballistic power. 
 The weights would be about the same, and the only difference 
 would be the expenditure of 41f Ibs. of powder instead of 
 33-081bs. 
 
 120. With reference to the higher pressure proposed to be 
 used it is to be observed that the maximum pressure in a gun 
 depends not so much on the charge of powder as on Sarrau's 
 characteristic a, or rather on a 2 , which is in his notation 
 
 = - , in which/ is the " force " of the powder, a a coefficient 
 
 T 
 
 depending on the form of the grain, r the time of total com- 
 bustion of the grain in free air. 
 
 121. It is, therefore, obvious that with any given powder 
 for which / has a fixed value, the value of a 2 may be 
 modified by a corresponding modification of a and r, the first 
 of which depends on the form of grain, the second on its 
 density and least dimensions. 
 
 It is, therefore, simply an object of research to make a 
 powder of which the characteristics a, will give the required 
 pressure. 
 
 122. As is easily seen, the higher pressure is given by the 
 lower value of r, whilst at the same time it may be effected 
 by giving such a form to the grain as will give a higher 
 value of a . 
 
 The practical result of decreasing r is that the evolution 
 of gas is quickened, and the pressure rises at an earlier 
 period of the course of the projectile, because the projec- 
 tile has not had time to move out of the way. 
 
 123. It is, therefore, evident that the question of the deter- 
 mination of the " characteristics " of these new powders, and 
 the size and form of grain suited to the different calibres 
 of guns, is one of first-rate importance, and without which 
 future ballistic progress must be a matter of hap-hazard 
 and danger. 
 
SMOKELESS POWDER. 39 
 
 VII. 
 
 CONCLUSION. 
 
 124. Whilst the superiority of the new powder is incontes- 
 table, there is a danger that must be guarded against. The 
 very fact of its being a more powerful agent renders 
 precaution in its use the more necessary. 
 
 125. Its enormous " force " may be practically mitigated in 
 two ways first, by the size and density of the grain, which 
 governs the rate of evolution of gas, and secondly, by a 
 low gravimetric density such as has hitherto been used. 
 By a due adaptation of these, the rate of evolution of the 
 gas has been so proportioned to the space behind the pro- 
 jectile, that the pressures have been kept down to the 
 moderate limit which the new type guns can resist ; but if 
 by any cause, such as a change of constitution of the powder 
 under great variations of climate, or by breaking up of the 
 grains during transport, the rate of evolution of gas is sud- 
 denly increased, then the very high " potential " of the 
 powder may give rise to sudden abnormal increase of pressure, 
 which the guns may be quite unable to resist, and serious 
 accidents may occur. 
 
 126. These new powders are certainly more liable to 
 such changes of composition than the old powders, which 
 are simply mechanical mixtures, and therefore it is the 
 more necessary that the guns should be strengthened to the 
 utmost, rather than fined down to meet the requirements of 
 anticipated low pressures. 
 
 127. The general conclusions which may be drawn from 
 the preceding remarks are as follows : 
 
 (1) That the smokeless powder has ballistic properties far 
 superior to the old powders. 
 
40 SMOKELESS POWDER. 
 
 (2) That the erosive action on the guns will probably be 
 less. 
 
 (3) That its use in existing guns of the new forged steel 
 type will not lead to any considerable increase of ballistic 
 effect without considerable risk, owing to the increase of 
 pressure developed in the front part of the chase, although 
 the actual maximum pressure on the gun may be less. 
 
 (4) That to utilise the high ballistic powers of the new 
 powders very strong guns will be required, and that such 
 guns will have to be much stronger in front of the trunnions 
 than those of the new type forged steel guns. 
 
 That to arrive at very high ballistic results it is not 
 necessary to have guns of inordinate length, but by the 
 adoption of higher initial, instead of low and more uniform 
 pressures, velocities of 3000 feet per second and upwards are 
 attainable with perfect safety. 
 
 128. In bringing these remarks to a conclusion, the author 
 may perhaps be allowed to give expression to opinions, which 
 in his own mind amount to convictions, as to the future of 
 gun construction and ballistic effects. 
 
 129. The first of these is, that low maximum pressure is a 
 mistake. It has no raison d'etre except the weakness of the 
 gun. It involves a length of gun which for naval use k is 
 most objectionable. No doubt M. Canet has achieved very 
 brilliant results with his 15 cm. Q.F. gun, but this gun is 
 23 feet 4 inches in length over all. A " similar " gun 
 of 12 inch calibre would be about 46 feet 8 inches long. 
 " Similarly " loaded it would fire a charge of B.N. powder 
 of 264 Ibs., and a projectile of 712 Ibs., with a muzzle velocity 
 of 2750 . feet per second, giving a muzzle energy of 37,330 
 foot-tons, or 848 3 foot-tons per inch of circumference. 
 
 Now, as was shown in ( 118), a 15 cm. gun of equal power, 
 firing with a maximum pressure of 30 tons per square inch, 
 would be 15 feet long, and a " similar " gun of 12 inch calibre 
 would be 30 feet long, as against 46 feet 8 inches for the 
 low pressure gun. There can be no doubt which gun is the 
 most suitable for naval service. 
 
SMOKELESS POWDER. 41 
 
 130. A second conviction is, that guns of a very large 
 calibre are a further mistake, and the author ventures to 
 think that a 9-inch or 10-inch high pressure gun would be 
 sufficient for any effect that is required against the heaviest 
 armour afloat. 
 
 131. A third conviction is, that in order to utilise the new 
 powders recourse must be had to the wire system of con- 
 struction, by which alone guns of sufficient strength can be 
 obtained. 
 
 132. Lastly, he would express the opinion that no time 
 should be lost in carrying out such a series of experiments 
 as will enable formulae analogous to those of M. Sarrau to 
 be constructed for these new powders, and also for the 
 determination of the tensile strain on the chase caused by 
 the friction of the products of combustion. 
 
( 42 ) 
 
 APPENDIX A. 
 
 DECOMPOSITION OF NOBEI/S POWDER AS A TYPE OF THE 
 SMOKELESS POWDERS. 
 
 According to Nobel's specification, No. 1471/88, 100 
 grammes of powder contain 
 
 Grammes. 
 
 Nitroglycerine 23-10 
 
 Nitrocellulose 23-10 
 
 Perchloride ammonia 50*35 
 
 Camphor 3-45 
 
 After explosion these give rise to new products, viz. : 
 
 From the Nitroglycerine. 
 
 Grammes. 
 
 Carbonic acid 13-435 
 
 Nitrogen 4-275 
 
 Oxygen -814 
 
 Water 4-579 
 
 Total .. .. 23-10 
 
 From the Nitrocellulose. 
 
 Grammes. 
 
 Carbonic acid 10-670 
 
 Carbonic oxide 6*791 
 
 Hydrogen -343 
 
 Nitrogen .. 3*112 
 
 Water 2-183 
 
 Total . 23-10 
 
APPENDIX A. 43 
 
 From the Camphor. 
 
 Grammes. 
 
 Carbon 2-81 
 
 Hydrogen 0-33 
 
 Oxygen 0-38 
 
 Total .. .. 3-47 
 
 From the Perchloride of Ammonia. 
 
 Grammes. 
 
 Chlorine 16-63 
 
 Oxygen 25-87 
 
 Nitrogen 6-47 
 
 Hydrogen .. .. 1-39 
 
 Total .. .. 50-35 
 
 . 
 
 Certain of the products of the camphor and perchloride 
 unite, and the final result of the decomposition is 
 
 Grammes. 
 
 Carbonic acid , 41-26 
 
 Nitrogen 13-86 
 
 Water 25-24 
 
 Chlorine 16-64 
 
 Oxygen 2-96 
 
 Total . 100-00 
 
 VOLUME OF GASEOUS PEODUCTS. 
 
 The volume of the products in the last paragraph at 
 Centigrade and * 76 metres of mercury would be 
 
 Cub. Decimetres. 
 
 Carbonic acid 20-87 
 
 Nitrogen 11-04 
 
 Watery vapour 31*31 
 
 Chlorine .. 8-21 
 
 Oxygen 2-08 
 
 Total . 70-51 
 
44 APPENDIX A. 
 
 Therefore, from 1 gramme of powder the volume of gas 
 = *7051 cubic decimetres, or 705*1 cubic centimetres. 
 
 In the above the water has been considered as in the state 
 of a permanent vapour, though of course that is impossible at 
 Centigrade, but as forming part of the products of com- 
 bustion it is always in the gaseous form, and may therefore 
 properly be comprised among the gaseous products, proper 
 allowance being of course made when the evolution of heat 
 is considered, for the heat absorbed in the vaporisation of 
 the water. 
 
 HEAT EVOLVED PER GKAMME OF POWDER. 
 
 Keverting to the 100 grammes of powder, the heat evolved 
 is that evolved in the formation of 42 26 grammes of car- 
 bonic acid and 25 24 grammes of water. The first contains 
 11-25 grammes of carbon, and the second 2 '80 grammes of 
 hydrogen. 
 
 Consequently the heat evolved is 
 
 From Carbon .. 11-25 x 8-08= 90 9 units Centigrade. 
 Hydrogen 2-80x34-46= 96-5 
 
 Total .. .. 187-4 
 
 but the heat required to vaporise 25 '4 grammes of water is 
 25-4 x '631 = 15-92 units Centigrade. 
 
 Deducting which there remains 171-48 units, or for 
 1 gramme of powder 1*7148 units Centigrade. 
 
 TEMPERATURE OF PRODUCTS. 
 
 This can only be given as a comparison with other 
 powders, and not as the real temperature existing in the 
 gun under circumstances when the loss of temperature due to 
 cooling and the specific heat at very high pressure and tem- 
 perature are both unknown. 
 
APPENDIX A. 45 
 
 The temperature now in question is what might be called 
 the potential temperature or the theoretic temperature, and 
 is calculated on the assumption that there is no loss by 
 cooling, and that the specific heat remains constant. 
 
 Under these conditions it may be compared with the 
 potential or theoretic temperature of ordinary powders. 
 
 NOBEL'S POWDER. MEAN SPECIFIC HEAT OP PRODUCTS. 
 
 Carbonic acid .. .. 41-26 x '172 = 7-097 
 
 Nitrogen 13-86 x '173 = 2-398 
 
 Watery vapour .. .. 25-40 x '337 = 8-506 
 
 Chlorine 16-64 x '086 = 1-431 
 
 Oxygen 2-96 x '155 = 0-459 
 
 100-00 19-891 
 
 Therefore the mean specific heat = 199. 
 
 TEMPERATURE. 
 
 Since the heat evolved is 1*7148 units per gramme, or 
 1714 * 8 units per kilogramme, the temperature will be 
 
 1714-8 
 
 -- = 8673 C. 
 
( 46 ) 
 
 APPENDIX B. 
 
 In order to compare with the Nobel powder, Pebble powder 
 is taken as a type of the old powders, and its composition, as 
 given by Noble and Abel in their * Kesearches on Explosives ' 
 (' Trans. Koyal Society/ 1880), is 
 
 Parts. 
 
 Saltpetre -7467 
 
 Sulphate (sic) -0009 
 
 Sulphur -1007 
 
 Carbon -1212 
 
 Hydrogen .. -0042 
 
 Oxygen '0145 
 
 Ash -0023 
 
 Water -0095 
 
 1-0000 
 
 And the products of combustion of 1 gramme at Cent, 
 and * 76 metres of mercury 
 
 Grammes. Vols. in cm. 3 
 
 Carbonic acid -2627 .. 132-9 
 
 Carbonic oxide '0468 .. 37-1 
 
 Nitrogen.. .. '1099 .. 87-5 
 
 Sulphydric acid -0109 .. 9'2 
 
 Marsh gas .. '0006 .. 0-8 
 
 Hydrogen -0006 .; 6-7 
 
 Watery vapour '0006 .. 11-7 
 
 4410 285-9 
 
 The remaining products consist of about 56 gramme of 
 salts, chiefly of potassium and sulphur, which whilst in the 
 gim are in the form of a liquid diffused throughout the gases 
 and at the same temperature. 
 
APPENDIX B. 47 
 
 HEAT EVOLVED. 
 
 The heat evolved from 1 gramme of powder is that due to 
 the combustion of the carbon and hydrogen in it. 
 The carbon is as follows : 
 
 Grammes. 
 
 From Carbonic acid .. -2627 X A = '0717 
 Carbonic oxide .. -0468 X -& = '0201 
 Marsh gas .. .. -0006 x f = -0005 
 
 Total 0-0923 
 
 The hydrogen is 
 
 In Sulphydric acid .. .. -0109 x T V = '00063 
 
 Marsh gas -0006 X | = '00009 
 
 Water -0006 X i = -00006 
 
 -0095 X i = '00106 
 
 Total -00184 
 
 Consequently the heat evolved is 
 
 Units. 
 
 From Carbon to Carbonic acid .. -0717 x 8-08 =0-5793 
 Carbonic oxide .. -0201x2-473= -0497 
 Marsh gas .. .. -0005 x 8-08 = -0041 
 Hydrogen -00184 X34-46 = -0634 
 
 6965 
 
 From this must be deducted the heat required to vaporise 
 the water, or 
 
 0101 x -631 = -0063 
 
 Total -6902 
 
 MEAN SPECIFIC HEAT. 
 This is given by Noble and Abel as 187. 
 
 TEMPERATURE (POTENTIAL OR THEORETIC). 
 The heat evolved from 1 kilogramme is 690 '2 units, 
 therefore temperature -7537" == 3690 Cent. 
 
APPENDIX C. 
 
 VELOCITY AND PRESSURE IN 5-905 INCH Q.F. CANET GUN WITH 
 54 LBS. P. POWDER. 
 
 Ballistic Elements. 
 
 c 
 
 I 
 
 w 
 
 W 
 
 A 
 
 Log o )8~ 
 
 Log o a 
 
 5-905 
 
 224-5 
 
 54 
 
 89 
 
 1 
 
 23014 
 
 43223 
 
 FORMULA FOR VELOCITY. (' Internal Ballistics, p. 137.) 
 
 V = 
 
 = m a p - 7 
 
 W^ 
 
 ; tnereiore 
 
 FORMULA 
 
 FOR PRESSURE : 
 
 P = Ka*A(^y 
 
 \ c 2 / 
 
 logM 
 
 2-84567 
 
 logK = -61174 
 
 >, * F* = 
 
 23014 
 
 a 2 = -43223 
 
 ,J W* = 
 
 64963 
 
 A = -00000 
 
 A^ = 
 
 00000 
 
 W^= -97470 
 
 c* = 
 
 09640 
 
 w^ = -86619 
 
 -* - 
 
 44055 
 
 
 
 Deduct 
 
 logV =3-40988 
 .-. V = 2570 f. s. 
 
 2-88486 
 Deduct 
 
 logc 2 = 1-54249 
 
 logP =1-34237 
 .-. P = 22-00 
 
POSTSCRIPT. 
 
 WHILST the above pages were passing through the press 
 I have read an interesting article, in the* United Service 
 Magazine ' of August 1890, by Professor Lewes, of the Eoyal 
 Naval College, on "The Present State of the Powder 
 Question." Agreeing generally in the Professor's con- 
 clusions, I must take exception to one or two of his remarks. 
 I do not agree that a perfect powder is one of which the 
 production of gas goes on until the projectile reaches the 
 muzzle of the gun. Such a powder would be very wasteful, 
 and would carry the region of high pressure much too far 
 forward in the gun. 
 
 Then, again, I think there must be some mistake in the 
 diagram which is given as representing the pressures in the 
 chase with the three powders P 2 , Bl. Prism, and Br. Cocoa. 
 The areas of the three curves A, B, and C, if correct, must 
 be proportional to the muzzle energies of the projectile. The 
 velocities are proportional to the square roots of the re- 
 spective energies, that is to say, to the square root of the 
 areas of the curves. 
 
 Now, these three curves are represented by the relative 
 numbers 69 * 5, 76, and 67 5, the square roots of which are 
 8-33, 8 72, and 8 22, respectively. 
 
 Consequently, assuming the velocity of 1608 feet per 
 second to be correct for the P 2 powder, the other velocities 
 as represented by the curves would be, Black Prismatic 
 1683 feet, and Brown Cocoa 1586 feet per second, instead 
 of 1708 and 1798 feet per second as given by Professor 
 Lewes. It is therefore evident that there must be some 
 mistake in the curves shown in the diagram. 
 
 I am very glad to see that Professor Lewes insists strongly 
 on the importance of the question of the stability of the 
 new powders. 
 
 H! 
 
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